I don't care for linear regulators. I had not planned on using it. Wasteful power wise. In my application, the regulator would use more power dropping the voltage to 5v than the rest of the circuit. I use a 14.4v LiPo for electronics power. I have other stuff that needs 12v.
This is what I have planned, but it will be powering two Arduinos and the ethernet shield. And I like to have extra, just in case.
http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_10001_155716_-1